<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="text" name="username" id="username"/>
    <input type="text" name="age" id="age"/>
    <button id="btn">添加</button>
</body>
<script>
    var userName=document.getElementById('username')
    var age=document.getElementById('age')
    var btn=document.getElementById('btn')

    btn.onclick=function(){
        userName=userName.value
        age=age.value
        var formData=new FormData()
        formData.append('username',userName)
        formData.append('age',age)
        fetch('http://localhost:8000',{
            method:'POST',
            body:formData
        }).then(res=>{
            return res.text()
        }).then(res=>{
            console.log(res)
        })
    }
</script>
</html>